The invention pertains to an on-axis light source for illuminating objects imaged by a machine vision camera. Robotic assembly machines may utilize video cameras to observe the parts or work pieces being handled and assembled and the invention pertains to the illumination of such objects.
For instance, in the assembly of electronic components the chips and wafers are often assembled to a printed circuit board by robots. The electronic components may include highly reflective surfaces which must be imaged by the machine vision camera, and the uneven reflection of light from the work piece will produce an erroneous image and signal within the camera possibly resulting in a malfunction or mismeasurement. Previously available illumination for robotic handled parts, particularly small parts, has not produced a light which is uniform over the entire part being imaged, and which is free of shadows and glare. Electronic components often utilize etched characters appearing on a mirror like surface and proper illumination of such components is critical if high quality printed circuit board assembly is to be achieved.
In the microelectronics industry, solder pads on surface-mount devices are often imaged for assembly and manufacturing purposes and the accuracy of the machine vision is critical for correct alignment of the many components which may be mounted on a printed circuit board. For optimum alignment, solder pads must be clearly imaged in high contrast with their background, and a need for improved illumination of objects being imaged by machine vision cameras has long been recognized.